Vehicle suspension.



B. LIEBOWITZ.

VEHICLE SUSPENSION.

APPLICAHON mm nov. 2.1914.

1,240,992 PatentedSept. 25,1917.

2 SHEETS-SHEET I.

Fig.3

1 l F795 Q I, Lwj U 2W as), M anemia) 8. LIEBOWITZ. VEHICLE SUSPENSION. APPLICATION HLE D NOV. 2' l9 1,240,992, PatentedSept. 25,1917.

2 SHEETS-SHEET Z BENJAMINLIEBOWITZ. OF NEW YORK. N. Y.

VEHICLE SUSPENSION.

Specification of Letters Patent.

Pateiit ed'itfiept 2 till Application filed November 2. 1914. Serial No. 869,725.

To all whom it may com-cm Be it known that l. BENJAMIN lai-znowrrz. a citizen of the United States and a resident of the city of New York. in the county of New York and the State of New Yorli. have invented certain new and useful Inn proyements in Vehicle Suspensions. of which the following is a specification.

My invention relates to the spring mounting interposed between the wheels of a vehicle and the body thereof. and is particn la'rly applicable to motor-trm-ks. or other automobiles.

One of the most important detects in the vehicle springs now connnonly in use is their comparativelv short life and consequent unreliability due to fatigue. which. as is well known, is caused by the severe and oft repeated stresses to which they are subjected. As mv experiments and observations have brought out. however. there is an even more important result of the fatigue phenomenon, and that is that severe and oft re )eated stresses impair the elasticity of springs and cause them to ride "hard" long before they may break. 7

The objects of my invention are: to provide a spring suspension which will respond freely to the roadsirregularities with the imposition of minimum force on the body: to enable the suspension to maintain this freedom of response throughout its useful life. by minimizing or entirely eliminating fatigue and its effects; to increase the life of the suspension so that it will'beas durable and reliable and to secure other advantages which will hereinafter be brought out. I accomplish these object's by means of a suspension in which the necessary elastic forces are obtained. not by merely altering the elastic configuration of the spring, but rather by altering the force components of an initially strained spring. with only incidental changes in its elastic configuration.

To illustrate what is meant. consider first an ordinary vehicle spring. 1f the spring has a stifl'ness of say 400 pounds per inch, and if a load of say 200 pounds is added, the spring will deflect one-half an inch. The loadincrease of "200 pounds is met, therefore, by a chan 'e in the configuration of the spring, 1'. 6., y a deflection of onehalf an inch. Consider, now, a violin string,

is the frame. for example i 'But this increase in stiffness means for example. It is under-considerable .ten' sion. butwhen at rest it exerts no forc pcrpcmlicular to itself. Let tlie s1-i'i|ig be pulled a little to one side. ;ho-wc\.'e| and ,a force perpendicular to the original position of the string is introduced. not by an increase in the tension oi' the string. for the change in tension is negligibly. small. but by the fact that the direction of the tension is changed so as to introduce a force component perpendicular to the original direction of the string. As long as the displaccment are small. the forces thus introduced are proportional to the displacements and arise without any appreciable change in the tension of the string. Musical strings. therefore. utter a simple example oi how elastic forces inay be obtained by a change in direction oi an almost constant force rather than by a change in elastic configuration. A yielding medium necessar in this case as well as in the preceding case. but the cleformations of the yielding body are merely incidental and. by a proper design. can be.

made very small. i

The matter may be viewed in. another light: since fatigue is due tothc large stress or strain range to which ordinary springs are subjected. it follows that it can be minimized or eliminated by suiiiciently reducing the strain range. 1 obtainfithis reduction by the use of certain types of spring motion reducing mechanism t-iall y strained springs. as will be explained. A spring motion reducing mechanism is one which converts a prescribed relative dis placement of body and axle into a .totalspring strain smaller than said displacement. 1n the case of an ordinary velnole spring, for example. a displacement of one inch of the axle relative to the body requires the spring. to deflect one inch; but by the use of a spring motion reducing mechanism, sa d dis )lacement requires a spring strainof only. a motion of an inch. Spring motion e ducin mechanisms have been employedibe fore. Eat without initial strain that are; insuflicient and practically useless. lfi-orit can readily be shown that when thesprings un dergo a reduced motiolrwithout being. initially strained, the stiffness of the'springs increased in order to t We! h iadx.

must be enormously enable the suspension iii-conjunction with .mi-'

portionate increase. in the stress range, so that whatever gain may result from reduc- 'in the spring strain is lost. Without initia strain, therefore, the analogy to the V The exact meaning of the above will be-.

come more clear by reference to'the accompanying drawings, in which- Figure 1 shows dia rammatically a side elevation, and

Fig. 2 a planof one embodiment of my invention;

Fig. 3 shows one of springs of Figs. 1 and '2 in its unstrained condition, and in its initially strained condition. Fig. 4 shows diagrammatically a side elevation, and I Fig. 5 a plan of another embodiment of my invention.

Fig. 6 shows diagrammatically a side elevation of still another embodiment;

Fig. 7 shows diagrammatically a type of frictional element.

Referring to Figs. 1 and 2, lrepresents a portion ofthe frame of a motor-vehicle.

The end of the frame shown is bent down' to form a bracket, 1 and another bracket, 1", is rigidly fastened to the frame 1, For the sake of clearness the frame 1 is not shown in Fi 2, and only the sections of the lower en s of the bracketslt nd 1 appear. 2 indicates the wheel, whic is shown merely by a dotted circle inFig. '1. To the axle 3 is rigidly fastened a collar 4, which collar is formed with the two arms, as shown.

Pivots 5 and 6 are carried by these arms,

,and the brackets 1 and 1 carry pivots and 8 respectively. The vehicle body is supported by the elastic tension'members 9 and 10, stretched between the pairs of pivots 5-7 and 68 respectively. These elastic tension members may be adpistable and may take a variety of forms; for example, thev may be simple helical tension-springs.

referred form of tension member is shown n Fig. 1, in which 9 represents. a cylindrieal casin 9 the connection between this casing and t epivot 7, 9 5 piston sliding in the casing, 9' the piston rod by. means of which the iston is connected to the pivot 5, and 9 a tension member 10 iscompose of similar parts. The parts 9 to 9sinelusive, comprise a tension member as' a whole} thatjs, they introduce the requisite tensile force between the pivots 5a1'1d 7; but the spring itself is elical compression-s ring. The.

under compression. 20 indicates a frictional element, the purpose of which and preferred forms of which will be hereinafter specified. To simplify thefigures the vehicle body is not shown in Figs. 1 and 2, but it is important to'note that the suspension is shown in a deflected configuration corresponding to. a loaded vehicle, either partly or fully loaded. A line ,A' .B is shown, drawn through. the'center of the pivots! and 8. As the bod rises andfalls, the line A B rises and fal swith it. If some of the load'is removed from the body, the frame rises a certain distance, dependin on the load re-. moved. This is accompanied by a rotation of the'tension members 9 and 10 about the pivots 5 and 6 respectively, so as to decrease the angle between the tension members. and the line A B, and b a decrease in the distance between line 'B and the pivot-centers 5 and 6. If all of the load were removed, and 'if the remaining parts were weightless and frictionless, the sus ension would assume the configuration in w ich all four pivots are on the straight line A B,- i. e., the one in which the tension members make zero angle with A B. We shall call this the no-load configuration. It is clear that in this configuration, the strain and the'tensile force of the tension members are a minimum.

.Although the suspension itself can sustain no load when in the no-load configuration, it is obvious that the springs thereof ma be under as much strain as desired. The is the strain whichI have called-the initial strain. In other words, an initia strain is a strain imposed on the springs of the suspension before the suspension as such supports any weight whatever. This initial strain is also the minimum strain to which the springs are subject, as pointed out above.

Referring-to Fig. 3, which serves to give the meaning of initial strain greater definiteness, 82 shows one'of the springs of Fig. 1

' in its normal or unstrained condition. This same spring, in its condition of initial strain under the no-load confi uration, is shown at 81. The difi'erence in tie'lengths of 81 and 82, which in Fig. 3 is designated as the distance 1,-is the initial strain towhich the} spring is subjected.

It is to be noted that as the suspension passes from the deflected confi ration of Fig. l to the no-load configuration, the de-' crease in the distance between the pivots 5 and 7 and between 6 and 8 is small, hence the increase -in the length of the springs is small. Hence the spring as shown at .81 of Fig. 3, in its condition of initial strain, is 2 the manner in which this tensile;f o rce 1s;

springs by the motion of .the body relative to the axle are *small compared tothe initialstraimhandlthis -is :essentialif the best results are to be obtained. (Jr, in other words,

.the tension of thetension members varies but l ttle in any small motion of. the body relat ve to the axle, in comparison with the initial tension, hence this spring stem, when .designedfor best results, ma'y iie described as one of nearly constant tension.

This isnot to be construed, however,- as

meaning that my invention is limited to very-large initial strains in comparison with the subsequent strains due to relative motion between body and axle, for. even with moderate initial strains, my invention gives improved results. It is pointed out that large initial strains are necessary forbest' results.

The analogyto the violin string will now.

be clear. Inthe no-load configuration, the

suspension acts as a string tightl stretched between the pivots 7 and 8, an exerts no vertical. force. The deflection of the suspension due to load, which corresponds to pulling the string aside, produces vertical components of the forces due to the tension members while only, slightl altering the tension of said tension memers. Thuswe obtain elastic forces by changes in theforce components of a strained body, rather than by changes in the elastic configuration of,

sive strain, as shown in Fig. 3. But if simple tensionsprings were used instead'of the;

arrangement shown at 9 and 10 in Figs. 1 and 2,.an elongation of the tension member would correspond to an elon tion of the spring, and in this case the initial strain in the spring wouldbe a stretch instead of a compressive strain. .The wordtension as used in this connection hereinrefers to the force exerted by the tension. members .be-;

tween their respective pivots irrespective-of produced.

The linkage shown inFigs.-1 and 2 has i been described herein asj'a spring-motion 12-, ducing mechanism, because, as is clear from' the foregoing, a given displacement of the body from its. equilibrium position in a change in the length of the tensiqn. members,.that is, ina spring-stra n, which is" small compared to Said displacementipro-f qthefiber stress range is generally ,vided that. the angleewhichthe tension members make with line A B are not too herein, .is the ratio of the dis lacement of the body to the chan e in the ength of the springs which said displacement produces. The reduction ratio may be more precisely defined as follows; i

Suppose that the body carrying a certain load is resting in equilibrium on its suspension. and that .the configuration of the suspension necessary to support the body in equilibrium under that load is that shown in Fig.1; if the'axle is now given Ea very small displacement dy, either up or down relative to the body, the length of the springs will be changed by an amount dam smaller than dy; the reduction ratio is then defined as the ratio d311, rim. It is easily. 1

shown from the principlesof mechanics that the reductionyratio thus defined is given by where is the angle which each tension member makes with the line A B; at; is,

"large. The reduction ratio, in the sense used the reduction ratio is inversely prop tional to the sine of the angle between thetehsionmember and the line A B. As the load on,

the bod is diminished the body rises and the ang e g diminishes, hence the reduction ratio becomesgrea-ter. It follows then that the lighterthe loadthe greater the reduc tion ratio.

varies inversely as the load.

In other. words, the reduction ratioof this suspension is not constant, butt p 1 4100 Inorder to illustrate by a concrete ex-' ample how my invention'reduces the strain range and the stress range in the material of thesprings, sup ose'that the initial strain is four inches an that a maximum fiber stress of 120,000pounds per square inch in thesprin material is caused thereby. Also, suppose t at the greatest subse uent strain, which the maximum allowable. i'splacement of axle relative to body causes, is one inch.

beonly on'e-fourthof the initial strain, and the fiber'stress'variation in the material will .be from 120,000ft0 150,000 pounds 'per' square inch, '5.- e., a maximum. fiber stress range of 30,000 pounds peruare inch. In

no Then the maximum subsequent. strain will ordinary vehicle springs, on t e other'hand,

three to" iiyeormoretimes this amount. a It should'be pointed out that even if'the springs of my suspension should have their. 0 ti ued service, the suspension as'a whole wgiild continueto act-with ap roximate perfectfelasticity. For since on ya compara tively small component of the spring force "acts on the bod so onl a comparatively small componen of any imperfectly elastic asticity'somewhatimpaired by long conforcewhichthe'springs themselvesmay ex-' art will be felt by the body. 4 Thisis one of.

. move in an arc of short radius, andv particuvantages.

larly when thatradius must be ad ustabIe, (as in the case of motor-vehicles having the double side-chain drive), the form shown in Figs. 1 and 2 resents certain disad- These disadvantages are overcome in the modification of my invention shown in Figs. -1 and 5, in which 1 is a portion of the vehicle frame, partly cut away in Fig.6 in order to reveal the spring mechanism; 2 is a wheel, indicated merely by a dotted circle in Fig. 4: 3 is the axle, which I appears in section in Fig. -l. To the under side of the frame are rigidly fastened the brackets 1*,1", 1 and 1. 1 and 1" appear in section in Fig. 5. while '1 and 1 are not shown in Fig. 5. The pair of brackets 1 and 1 carry the rod 11. and the pair 1 and 1 carr the rod 12. The rods 11 and 12 are in alinement. Sliding freely on rods 11 and 12 are the sliders 13 and 14, which.

U The carry the pivots 7 and 8 respectivelv collar -1 is rigidly fastened to the axle 3,

and carries the pivots 5 and 6. Pivoted at- 5 and 7 is the tension member 15, and pivoted at 6 and 8. is the tension member 16. These tension members are shown as frameworks, each made up of two rods rigidly connected together at or near their ends; this construction gives sidewise rigidity to the body of the vehicle. Spanning the rods 11 and 12 and sliding freely thereon is the yoke 19. Between the slider 13 and the yoke-19 is a long. heavy, helical compression spring 17, and likewise between 11 and 19 is the spring 18. 20 indicates a frictional element, the pur use of which and preferred forms of which will be hereinafter specified. 21 is the pivot of the radius .rod which compelsthe wheel-center to move constraint of the radius rod R is removed,-

in the arc MN shown in Fig. 4. The radius rod,is indicated by the dashed line H with arrowhead. a

In order to exhibit the construction more clearly in Fig. 4, the bracket 1 and the yoke 19 are shown partly in section, the slider 14 and the spring 18 are shown wholly in section, most of the tension member 16 is cutaway, and the pivot 8 is not shown.

It is clear from the foregoing that if the the wheel-center can move fore and aft parallel to the line A B as far as the limits of the mechanism 'permit. As the wheelcenter moves parallel to A B it carries with itthe spring suspension proper,- that'is, the tension members, sliders, sprm' The radius rod may take any and yoke, I t

" gnl he g ever-arm, 5 and which 130 Furthermore, the motion of the wheelcenter in the are MN can be decom osed into two motions, one parallel to an one perpendicular to the line A B. The latter motion istaken care of by the spring suspension proper; the motion paral 01 to A B is taken care of by motion of the s ring suspension as a whole parallel to A as described. i

The line A B has the same significance as I the line A B of Fig. 1; Just as in the case of Fig. 1, the sus ension shown in Fig. 4.-

is under load. I all load were removed from the suspension, then in the theoretical case of a weightless, frictionless suspension the configuration would be assumed, in which all four pivots, 5, 6, 7 and 8 are in the line A B; that is, the no-load configuration. lVhen the suspension is in this state, the springs can be underas much compression, that is, the tension members under as much tension, as desired. This compression and tension are the initial strain and the initial tension which have been fully described in connection with Figs. 1, 2 and 3. The unstrained length of the springs 17 and 18 of Figs. 4 and 5 are not shown, but it is to be -unc erstood that these springs are under an initial strain which is large in comparison with the additional strains caused by relative motions between body and axle; a condition which, as already noted, is essential for best results.

The remarks which have been made concerning the operation of the suspension shown in Figs. 1 and 2 are equally applicable to the suspension shown inFigs. 4 and 5. The only difl'erence to be noted is that for a given angle between the tension members and the line A B, the reduction ratio of the suspension shownin Figs. 1 and '2 is slightly greater than that of the suspension shown in Fi s. 4 and 5.

By rigidly fastening the yoke 19 to the nods 11 and 12, the suspension shown in Figs. 4 and 5 may be adapted for use on the front axle or on shaft driven. motor vehicles The two embodiments of my invention, which have so far been described have very similar sprin -motion reducing mechanisms. In or er to illustrate how widely the' type of the reducing. mechanism.may be varied in my invention, I have shown in Fig. 6 a side elevation of another embodimentt In Fig. 6, 1 represents part of the frame of the vehicle, 2 indicates the circumferenoe ofthewheel, and 3 shows the axle (in section). 5.-5" is a heavily built lever which is pivoted to the frame at 6. The pivot 6 is carried by the bracket 1', which is partof frame. Lisa collar whichis 'incarried by.

fastened to the a 3. 7 isa pivot is; another piv,ot carried by the, frame.

v7 and 8 are all on spring thereof can sustai Stretched between the tensionmembcr 9.; simi ar inconstruction to the tension members 9 and 10 of ,Figs. 1.

and 2. is a frictional element, which will. be more fully described hereinafter.

In Fig. 6, as revious fi es, the sus e'nsion is suppose to be uh. ine A B, drawn through the, pivot 6 and 8, has thesame significance as centers heretoforei when the three-pii'ot-ci anters 6,

the line A B the suspension can sustain no load and is therefore in the no-load configuration. But with the 811551151011 in the nodoad configuration the an initial strain as large as desired, and it-is to be understood that sucli'airinitial'strain isjmposed w ijchv should be large in comparison with, the subing is sub- It is 0 ar mm the figure that a given motion of the wheel-center; relative/t o the bodyproduces a relatively :small deformation of the sprin ,hence this a The analogy suspension like 'sp' ing-inotion. reducing mechanism of -mjemb'cr 9 about the same axis.

those reviou y described for its fun ament'al "elements:1 a

ecreasing reduction-ratio with increasing load and an' initially, strained spring system cooperating therewithr' between the sus aension of Fig. 6 and the violin string may be pointed out. In equilibrium, the moment'abou't pivot-6 due to the upward reaction of the axle is; equal to the moment of the tension The latter moment is equal to the prodiict of the distance between pivotce nters 6-7 the com onent of the tension pendicu ar to the line drawn pivot-centers 6-7. component her in, has

member perthrough the pivbtcenters 6-4. when the pi 'ot-centers 6, 7, 8 all lie on the line A B,'this supporting component is evidently zero, hence the sus ension can exert l'lO Sll)[)0It1l'lg force andhs therefor in the noloa This correspondsto the stretched violin stringin its normalposition. As load comes on the sus )ensiointhe, an le between the tension mem' er and the inc 6- 7 increases from zero, and the tension member therefunction fairly satisfactorily, is shown in Hence the suspension ivots 'Z and 8 is'the.

r load. The

Suppose a weight hung motion also, that is, the

[greater or less extent. These are multiplied by 'lations from attaining a Hence the supporting of the. tension member is its component perpendicular to the line through configuration.

materially altering;

of Fig. 6, like t ose de- I The rehic e suspensions which been described are each frictional element der to completely understand the function which these frictional elements have to per-- "form, it is necessary to. distinguish between two types ofoscillations which a suspended shown equipped with a designated as '20. In or.-

system, like a vehicle body, can perform.

from a fixed point by a spring is displaced vertically from'its equil brium position and then released;. the weight will then undergo oscillations of decreasing amplitude until it finall comes to rest. These are the free oscillations of the we l t. But if the point of support, instead of enig fixed, is made to undergo simple harmonic motion, the wei' lit will ultimately settle down to a state 0 weight will follow the motion of its point of support to a the forced oscillations of the weight. The body of a 'vehicle in motion may be regarded as a weight hung by a 5 ring from a support (viz., the axles), w "ich is under oing a combination of a harmonic motions. capable of performin oscillations. When tie amplitude is small, the free oscillations are not articularl objectionable. But free oscil ations of in amplitude and forced oscillations of any but very small amplitude are highly objectionable, and it is the object of every iehicle' suspension to eliminate them as far as possible. In order to prevent the free oscillarge amplitude,

A vehicle body, then, is

simple harmonic I great variety 0 simple Y ener v-dissipating forces of some kind, that the body and of free oscillations within suitable limits without. causing a notable increase in the forced oscillations.

A frictional element" which, if properly constructed and adjusted, will perform this Fig. 7. Here 42 is a pair of pivoted sliding frictional surfaces, one disk of which carries the; arm 43 and the other the arm 44.

The arm' 43'is "itoted tb the -frameaof the vehicle at 41. he free'end of the arm 44 is forked as shown. 3 is the axle which carries the pin 45. Owing to the fork-and-pin arrangement, the frictional element is not called into play until the amplitude of the motion of the 'azile relativeto the body exceeds a certain value, hence .this frictional element will have no eflect on the forced vibrations so long as the axle motions are small, and, if properly adjusted, will keep the free oscillations within required limits. The frictional element described is. not the only one which may be used in my invention. There are certain types of frictional shock- "10 absorbers on the market at the present time oscillations. It should be pointed out, however, that the ability to minimize the fric tion in the suspensio'n'itself and to reintroduce the friction in a controlled manner is one of the advantages of myinvention.

The term strain is used herein in. its usual sense to denote change of shape or deformation. When applied to a helical spring it means elongation or com ression; to an elliptic spring it means de ection; and so forth, for the different types of springs which may be employed. The term stress is used in its usual sense to' denote the force associated with the strain. The term spring-motion reducingkmechanism is used herein to denote any lin age or other mechanism which-converts a prescribed motionthe relative displacement of body and axle 40 into aresulting smaller motion-the com pression or elongation or deflection of the spring or springs.

does not include all reducing. mechanisms; it

includes only those in which the reduction ratio varies inversely as the load.

It is to be understood that such expressions as normal range of relative displacements of body and axle and normal relative displacements of body and axlef, etc, 9 refer to displacements due to load carried by the vehicle, plus those due to gassing over ordinary road irregularities. placements, such as are due to large irregularities in the road, may be included, but are not necessarily included.

The term nearly constant strain, as used herein, is intended to include strain variations which, inthemselves, may not be very smalhbut whiglymre small in comparison with the strain ,variations to' which ordinary vehicle s rings lare', s ubjectedl A slmilar latitude o defillliligxldlqtlld be allowed to the terms nearly, eenstant stressfletc.

I amnwarqthat suspensions superficially similar to mine have been devised, but sd-Qar My invention, however,

xtreme .dis-

placements of body and axle.

duce the stress and strain range in vehicle springs byemploying reducing mechanisms of reduction ratio varying inversely as the load, in conjunction with initially strained springs. Theseare the broad aspects of my inventions, which is not to be construed as limited to the specific embodiments described herein. a

The terms spring and springs as used in the specification and claims are intended 35 to include'metal or solid springs or some.

suitable equivalent other than fluid springs. lVhat I claim is: E 1-. In. a. vehicle suspension, the combination of an initially strained spring and a 90. spring-motion reducing mechanism of reduction ratio varying inversely as the load,"

whereby. the spring material is subjected'to reduced stress variations.

2.- In a vehicle suspension, the oombination of an initially strained spring, the ini- .tial. strain whereof is large in comparison with the subsequent. strains due to normal relative displacements of body and axle, anda spring-motion reducing mechanism of reduction ratio varying inversely as the load, whereby the spring material is subjected to reduced stress variations. 1 3. In a vehicle suspension, the combination of a plurality of initially strained. springs, and a spring-motion reducing machanism of reduction ratio varying inversely as the load, whereby the spring material is subjected to reduced stress variations.

4. In a vehicle suspension, the combination of a plurality of initially strained springs, the initial strains whereof are large in comparison with" the subsequent strains due to normal relative displacements of body and axle, and a spring-motion reducing mechanism of reduction ratio varying inversely as the load, whereby the spring material is subjected to reduced stress variations.

5; In a vehicle suspension, an initially 12o strained spring under nearly constant strain throughout the normal range of relative dis- 6. In a vehicle suspension, the combination with a pair of pivots, one fastened to the body and the other fastened to the axle, of a tension member extending between the, pivots and being under, nearly constant tension throughout the normal range of relative displacements of body and axle.

7. In a vehicle suspension, the combination with a plurality of pivot pairs, one pivot of each pair being carried by the body and the 'other by the axle, of a plurality of tension members under nearly constant tension throughout the normal range of relative displacements of body and axle, each tension member extending between a pivot palr.

8. In a vehicle suspension, the combina tion with a pair of pivots, one fastened to the body and the other fastened to the axle,

' of a tension member extending between the pivots, and an initially strained spring adapted to maintain said tension member under nearly constant tension throughout the throughout the normal range of relative displacements of body and axle.

10. In a vehicle suspension, the combination of a tension member, and an initially strained spring forming a part of said tension member and adapted to maintain said tension member under nearly constant tension throughout the normal range of relative displacements of body and axle.

11. In a vehicle suspension, the combination of an initially strained spring, and an angularly movable member co-acting therewith in supporting the body and adapted to reduce the subsequent strains produced in said spring by normal relative displacements of body and axle.

12. In a vehicle suspension. the combination of a system of initially strained springs, and a plurality of angularly movable members co-acting therewith in supporting the body and adapted to reduce the subsequent strains produced in the springs by normal relative displacements of body and axle.

13. In a vehicle suspension, a pair of spring tension members under nearly constant strain, each pivoted to both body and axle and arranged for bodily angular motion upon displacement of either or both of said parts from equilibrium.

l-L- In a vehicle suspension, a pair of initially strained elastic tension members each pivoted to both body and axle and: arranged t'or bodily angular motion upon displacement of either or both of said parts from equilibrium.

15. In a vehicle suspension, the combination with an axle and a frame of a pair of pivots rigid with the axle, a second pair of pivots depending from the frame at opposite sides of and below the axle pivots, and a pair of initially strained elastic tension members each stretched between an axle pivot and a frame pivot and adapted to support the frame on the axle.

16. A vehicle suspension comprising, initially strained springs, a spring-motion reducing mechanism of reduction ratio vary ing inversely as the load cooperating therewith for reducing the subsequent strains produced in said springs in comparison with the relative displacements of body and axle causing said subsequent strains, and frictional means for checkin the free oscillations of the suspended bo y.

17. A vehicle suspension comprising, initially strained springs, means. cooperating therewith for reducing the subsequent strains produced in said springs in comparison with the relative displacements of body and axle causing said subsequent strains, the reduction ratio of said means varying inversely as the load, and frictional means operative to check the free oscillations of the suspended body 'when they exceed a predetermined amplitude.

18. The method of reducing stress variations in the material of spring suspensions,

which consists in initially straining the spring or springs of the suspension and in subjecting said spring or springs to reduced subsequent strains by means of a spring-motion reducing mechanism of reduction ratio varying inversely as the load.

19. The method of supporting a vehicle body upon its axles by means of a spring suspension, which consists in initially straining the spring or springs of the suspension, and in altering the supporting components of the forces due to said spring or springs, upon application of load, without materially altering the elastic configuration of the spring or springs.

20. T to method of supporting a vehicle body upon its axles by means of a spring suspension, which consists in subjecting the spring or springs of the suspension to an initial strain which is greater than the subsequent strains due to normal relative displacements of body and axle, and in altering the supporting components of the forces due to said spring or springs, upon application of load.

In testimony whereof I have hereunto aflixed my signature in the presence of two subscribing Witnesses.

BENJAMIN LIEBOIVITZ. Witnesses:

LESTER F. Drrrnnnonrnn, GRACE M. RIVIERE. 

